Use retries: true for apt install on Travis
Use retries: true for apt install on Travis

smharper/openmc,johnnyliu27/openmc,paulromano/openmc,mit-crpg/openmc,liangjg/openmc,amandalund/openmc,paulromano/openmc,shikhar413/openmc,liangjg/openmc,johnnyliu27/openmc,walshjon/openmc,johnnyliu27/openmc,shikhar413/openmc,walshjon/openmc,amandalund/openmc,smharper/openmc,shikhar413/openmc,mit-crpg/openmc,wbinventor/openmc,paulromano/openmc,amandalund/openmc,paulromano/openmc,shikhar413/openmc,johnnyliu27/openmc,walshjon/openmc,walshjon/openmc,wbinventor/openmc,wbinventor/openmc,mit-crpg/openmc,amandalund/openmc,wbinventor/openmc,mit-crpg/openmc,liangjg/openmc,smharper/openmc,smharper/openmc,liangjg/openmc